Air collector with functionalized ion exchange membrane for capturing ambient CO2

ABSTRACT

An apparatus for capture of CO2 from the atmosphere comprising an anion exchange material formed in a matrix exposed to a flow of the air.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority from U.S. ProvisionalApplication Ser. Nos. 60/780,466 and 60/780,467, both filed Mar. 8,2006, the contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention in one aspect relates to removal of selected gasesfrom air. The invention has particular utility for the extraction ofcarbon dioxide (CO₂) from air and will be described in connection withsuch utilities, although other utilities are contemplated, including thesequestration of other gases including NO_(x) and SO₂.

There is compelling evidence to suggest that there is a strongcorrelation between the sharply increasing levels of atmospheric CO₂with a commensurate increase in global surface temperatures. This effectis commonly known as Global Warming. Of the various sources of the CO₂emissions, there are a vast number of small, widely distributed emittersthat are impractical to mitigate at the source. Additionally, largescale emitters such as hydrocarbon-fueled power plants are not fullyprotected from exhausting CO₂ into the atmosphere. Combined, these majorsources, as well as others, have lead to the creation of a sharplyincreasing rate of atmospheric CO₂ concentration. Until all emitters arecorrected at their source, other technologies are required to capturethe increasing, albeit relatively low, background levels of atmosphericCO₂. Efforts are underway to augment existing emissions reducingtechnologies as well as the development of new and novel techniques forthe direct capture of ambient CO₂. These efforts require methodologiesto manage the resulting concentrated waste streams of CO₂ in such amanner as to prevent its reintroduction to the atmosphere.

The production of CO₂ occurs in a variety of industrial applicationssuch as the generation of electricity power plants from coal and in theuse of hydrocarbons that are typically the main components of fuels thatare combusted in combustion devices, such as engines. Exhaust gasdischarged from such combustion devices contains CO₂ gas, which atpresent is simply released to the atmosphere. However, as greenhouse gasconcerns mount, CO₂ emissions from all sources will have to becurtailed. For mobile sources the best option is likely to be thecollection of CO₂ directly from the air rather than from the mobilecombustion device in a car or an airplane. The advantage of removing CO₂from air is that it eliminates the need for storing CO₂ on the mobiledevice.

Extracting carbon dioxide (CO₂) from ambient air would make it possibleto use carbon-based fuels and deal with the associated greenhouse gasemissions after the fact. Since CO₂ is neither poisonous nor harmful inparts per million quantities, but creates environmental problems simplyby accumulating in the atmosphere, it is possible to remove CO₂ from airin order to compensate for equally sized emissions elsewhere and atdifferent times.

Various methods and apparatus have been developed for removing CO₂ fromair. In one prior art method, air is washed with a sorbent such as analkaline solution in tanks filled with what are referred to as Raschigrings that maximize the mixing of the gas and liquid. The CO₂ reactswith and is captured by the sorbent. For the elimination of smallamounts of CO₂, gel absorbers also have been used. Although thesemethods are efficient in removing CO₂, they have a serious disadvantagein that for them to efficiently remove carbon dioxide from the air; theair must be driven past the sorbent at fairly high pressures. The mostdaunting challenge for any technology to scrub significant amounts oflow concentration CO₂ from the air involves processing vast amounts ofair and concentrating the CO₂ with an energy consumption less than thatoriginally generated the CO₂. Relatively high pressure losses occurduring the washing process resulting in a large expense of energynecessary to compress the air. This additional energy used incompressing the air can have an unfavorable effect with regard to theoverall carbon dioxide balance of the process, as the energy requiredfor increasing the air pressure may produce its own CO₂ that may exceedthe amount captured negating the value of the process.

Such prior art methods result in the inefficient capture of CO₂ from airbecause these processes heat or cool the air, or change the pressure ofthe air by substantial amounts. As a result, the net loss in CO₂ isnegligible as the cleaning process may introduce CO₂ into the atmosphereas a byproduct of the generation of electricity used to power theprocess.

The present invention in one aspect provides an improvement over priorart systems for removal of CO₂ from air by the utilization of solidphase anion exchange membranes for the direct capture of CO₂ and otheracid gases such as NO_(X) and SO₂ from air. Specifically, this inventionprovides practical physical configurations of the active element,processes for the manufacture of the active element and configurationsoptions of an air collector device to facilitate the direct capture ofCO₂ and other acid gases from the air based on solid phase, anionexchange materials.

SUMMARY OF THE INVENTION

This invention in one aspect provides practical physical configurationsof active air contacting elements, processes for the manufacture of theactive elements and configurations options of an air collector device tofacilitate the direct capture of CO₂ and other acid gases from the airbased on solid phase, anion exchange materials.

The air capture device in accordance with the present inventionconstitutes a front-end component of a larger system designed to capturelow concentration ambient CO₂, chemically remove the captured CO₂ fromthe air capture device, concentrate the CO₂ for subsequent permanentdisposal, reconstitute the process chemicals and reactivate the CO₂capture materials in preparation for the next capture cycle.

The air capture device utilizes a functionalized anion exchange polymerthat is formed to provide a relatively large surface area which allowsfor air flow with minimum resistance. In one embodiment the anionexchange polymer takes the form of an open matrix or unordered mesh of“noodle-like” strands, e.g., similar to those found in evaporative orhumidifier pads. Alternatively, the anion exchange polymer is formedinto cells or coated on surfaces of a support material formed into cellsthat provides certain critical capture performance requirements.

In our co-pending PCT Application Serial No. PCT/US06/029238, filed Jul.28, 2006, we describe specific requirements for the chemical performanceof the solid phase ion exchange material. This application in one aspectaddresses mechanical configurations and air-side performanceenhancements to ensure that the low energy needs of the overall systemare met while ensuring a robust design with repeatable air captureperformance. In another aspect, this application describes an integratedsystem for reforming CO₂ into other molecules that will permanentlyprevent the reintroduction of the captured CO₂ into the atmosphere.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the present invention will be seenfrom the following detailed description, taken in conjunction with theaccompanying drawings, wherein

FIG. 1 a flow diagram illustrating a capture of CO₂ from the air;

FIGS. 2a-2f are cross-sectional views schematically illustrating variousconfigurations of air capture media in accordance with the presentinvention;

FIGS. 2g and 2h are perspective views illustrating “noodle-like” aircapture media in accordance with the present invention;

FIGS. 3a, 3b and 4 are perspective views illustrating variousembodiments of air capture media in accordance with the presentinvention;

FIG. 5 schematically illustrates air capture media installed in acooling tower in accordance with the present invention;

FIG. 6 is a schematic view showing air capture media installed in anexhaust system in accordance with the present invention; and

FIG. 7 is a schematic view illustrating CO₂ capture from the airfollowed by sequestration in accordance with a preferred embodiment ofthe invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

One goal of the air capture device of the present invention is topresent a maximum amount of surface area of the solid phase ion exchangematerial per unit volume to a high volume flow rate, low pressure airstream while minimizing air pressure drop across the device.

Preferably, the air capture device also is configured to ensure ascomplete as possible penetration and thorough liquid contact of allsurfaces with a sorbent chemical to remove the captured CO₂ and toreactivate the membrane surfaces.

In operation, the air capture device will be exposed to a stream of airfor a given period of time until, through known performancecharacterization, it will be necessary to remove the capturedcarbon-bearing molecules and reactivate the solid phase anion exchangematerials. The solid phase anion exchange materials will then betreated, for example with a sorbent chemical, e.g. through liquid bathimmersion or spray, to remove the carbon-bearing molecules andreactivate the solid phase anion exchange materials. Once drained, theair capture device can be reintroduced to the air stream.

Preferably, the air capture device is oriented to the air stream withits major feature or face substantially perpendicular to the air streamflow path. The face is penetrated by a matrix of passages that areparallel with the principal axis of the air stream and that passcompletely through the bulk of the air capture device.

As stated previously, the amount of energy expended by the air captureand cleaning process to capture and concentrate atmospheric CO₂ must beminimized. To be viable, the process should introduce less CO₂ into theatmosphere as a byproduct of the generation of electricity used to powerthe process than that amount of CO₂ that is captured. This impacts theconfiguration of the air capture device, specifically its aerodynamicimpedance to the incoming process air stream.

The ideal arrangement of the device will be to utilize available winddriven airflow without fan assistance; however, the case for fanassisted airflow must also be considered. Given that a known amount ofair must be processed to extract a known amount of CO₂ (on the order of10,000 units of air to every unit of CO₂) and that the impedancepresented by the air capture device will have a direct influence on thefan input power, it is necessary to minimize air-side pressure dropthrough the device. This may be achieved through the design of lowpressure drop features that communicate air from inlet to the outletfaces of the air capture device with low flow resistance.

In competition with the above requirement, another critical criterionrequires the maximization of the specific active surface area of thedevice. Expressed as the unit active area per unit volume of the bulkmass of the device, one goal of the present invention is to limit theoverall physical size of the air capture device. The concern arises fromexperimentally derived CO₂ capture flux values for the ion exchangematerial under consideration. Although relative to other CO₂ capturemethodologies, it performs very well, and flux values are quite low.Specifically, we have demonstrated average capture fluxes from 2 to 6E-5moles CO₂/m²/sec. This has a significant impact on the amount of surfacearea of active material necessary to achieve practical capturequantities. For example, at 2E-5 moles CO₂/m²/sec with the goal ofcapturing 1 tonne of CO₂/day, the device would be required to expose13,150 m² of membrane to the air stream. Thus, the device needs to beconfigured with a high specific active surface area matrix to achieve apractical device without severe limitations on its location owing to thecollector size.

A third criterion is the ability of the structural matrix to bethoroughly wetted by the sorbent chemistry necessary to remove thecaptured CO₂ and to refresh the active material. Commensurate with itsability to be easily and thoroughly wetted is its ability to completelydrain in preparation for the next processing cycle.

A fourth criterion requires that the structural matrix be configured topresent a robust, uniform and dimensionally stable form. This isnecessary given the following factors:

-   -   1. Firstly, the material may undergo significant dimensional        variations owing to expansion and contraction processes between        the wet and dry states. The fabrication of the matrix must        provide robust joints between subcomponents to withstand the        repeating strain over years of cycling without tear or rupture.    -   2. The design of the internal features must accommodate the        expansion and contraction while maintaining dimensional        stability. This is necessary in order to avoid localized and/or        gross reductions in cross-sectional area as presented to the air        stream which would lead to a reduction in the exposed active        membrane.

Very high specific active surface area will compete, however, with therequirements for low pressure drop, this arising from the fact that highsurface area to volume efficiencies are achieved with very smallinternal features or passages. Additionally, very small internalfeatures may also compromise air flow by causing air stagnation in thesefeatures below a characteristic critical air flow.

Thus, the final design and configuration will be an optimization ofpressure drop, specific active surface area and overall collector size.This will also be influenced by practical manufacturing processesnecessary to make a robust and cost effective device.

Design and Configuration of Active Element

a. Requirements Overview

The air capture device of the present invention comprises a field ormatrix of active elements or features that communicate directly betweentwo opposing faces in such a manner as to minimize energy loss owing toaerodynamic forces arising from airflow through these features. In oneembodiment of the invention, the active elements or features take theform of an open matrix or unordered mesh of “noodle-like” strands,similar to those found in evaporative or humidifier pads. In anotherembodiment of the invention the active elements or features arecomprised of repeating shapes such as, but not limited to, regular andirregular polygons that may be of varying sizes and shapes occupying thecomplete matrix. The shape, size and distribution may vary over theentire matrix in order to optimize the airflow characteristics andpressure drop distribution to achieve the desired capture kinetics andstructural performance criteria noted previously.

b. Physical and Performance Attributes

The smaller the cross-sectional area of a given feature, the higher thespecific area of a unit volume of the matrix, i.e., specific area beingthe ratio of area to volume. For example for a matrix of rows ofequilateral triangles, 5 mm on each side, each row separated by a planarsheet would have a specific area of approximately 1200 m²/m³. A matrixof 10 mm equilateral triangles would present a specific area ofapproximately 600 m²/m³.

The trade-off of a small feature size is that with the air-sideaerodynamic characteristics of turbulence and pressure drop. For a givenairflow, as the cross-sectional area of the feature is reduced, theturbulence and pressure drop along the air path length will increase. Toa limited extent, turbulence is desirable to ensure good CO₂ capturekinetics with a solid phase anion exchange material. However, a cost forhigher turbulence and commensurate pressure drop though is the higherenergy required to move the air through the air capture device. For agiven surface roughness of the solid phase anion exchange material incontact with the process air, the significant performance trade-offvariables are feature cross-sectional area and uniformity, flow pathlength, air velocity flux at the face of the matrix and CO₂ capturekinetic response of the solid phase anion exchange material,

Overlaying these performance trade-off issues are those related to themanufacturing and assembly of the features and the matrix. Themanufacturing process necessary to create the small features whileensuring a robust and consistent assembly will be reflective of thestarting raw materials. The two most common forms of solid phase anionexchange materials are thermoplastic sheet and beads. The practicalityof forming small features will be driven by available processes andpractices given these materials. There may be certain feature sizes,below which the manufacturing process may need to change potentiallyresulting in higher unit costs.

c. Configuration Options

At the most discrete level, the repeating feature would be comprised ofrepeating shapes such as, but not limited to, regular and irregularpolygons that may be of varying sizes and shapes comprising the completematrix. The selection of shape would be influenced, in part, by thespecific area requirements and manufacturability. Additionally, theoverall configuration of the air capture device may dictate more thanone feature shape in order to maximize exposure to the air stream andadjust for differential air velocity fluxes. Potential shapes include,but are not limited to, isosceles and equilateral triangles, trapezoids,squares, rectangles, other regular and irregular polygons. See, e.g.FIGS. 2a-2f . The shaped anion exchange material may be formed fromsheets of anion exchange material such as functionalized polystyrene orthe like, or comprise sheets of inert substrate material coated withanion exchange material. Alternatively, and in a preferred embodiment ofthe invention, the anion exchange material comprises “noodle-like” 1 mmthick by 1 mm wide strands formed by slitting commercially availableanion exchange membrane material. One currently preferred material is ananion exchange membrane material available from SnowPure, LLC, SanClemente, Calif. The manufacturer describes these membrane materials ascomprising crushed anionic exchange resin mixed in a polypropylenematrix and extruded as a sheet according to the teachings of U.S. Pat.Nos. 6,503,957 and 6,716,888. The “noodles” or strands are formed byslitting 1 mm thick sheets of SnowPure anion exchange material into 1 mmwide “noodles” or strands. (See FIGS. 2h-2i ).

In accordance with one embodiment of the invention, an air capturedevice may be formed in a substantially circular shape and constantthickness shape, i.e., a disc, using a matrix of polygons which follow aspiral pattern to take advantage of a continuous strip of corrugatedsolid phase anion exchange material that is as wide as the air capturedevice is thick. See, e.g. FIGS. 3a and 3b . The unit would be woundwith a continuous corrugated layer and a co-joined planar layer untilthe desired diameter is achieved. An alternative to this configurationwould be discrete increasingly larger diameter annular segments ofcorrugated solid phase anion exchange material and planar sheetsubassemblies that would fit snugly together until the desired diameterof the air capture device is achieved.

A variant of the above example would have a disc of variable thickness.See, e.g. FIG. 4. This may be desirable in the presence of a non-uniformair flux field in order to ensure uniform capture and/or aerodynamicperformance throughout the mass of the air capture device.

One advantage of the circular cross-section would be to match thegeometry of the air capture device to a cooling tower such as anup-draft cooling tower which is circular in cross-section as well. See,e.g. FIG. 5. This circular feature also lends itself to retrofitapplications of existing cooling tower installations.

Another configuration for the air capture device would be substantiallyrectangular, e.g., as shown in FIG. 6. The matrix would consist of afield of regular, repeating polygons set in rows or columns separatedfrom each other by planar sheets. An alternative arrangement wouldinclude substantially a field of regular polygons with discretely placedregions of alternate shapes, patterns and/or sizes to optimize the CO₂capture kinetics and aerodynamic performance throughout the mass of theair capture device. One advantage to this configuration is that it lendsitself to an installation into a standard shipping containerfacilitating the development of a stand-alone, integrated andself-contained device that is readily shipped via the existingintermodal transportation infrastructure.

In all the configurations previously discussed a significant advantageto the matrix arrangement of the polygon-based features is its inherentstructural stability and strength. In the planar sheet form, the solidphase anion exchange material has no practical structure for stabilityand low specific area and in the bead form, the solid phase anionexchange material has high pressure drop and requires externalcontainment structures. A fabricated matrix of solid phase anionexchange material or a substrate coated with an anion exchange materialcreates a space frame structure similar to that used in aircraft floorsand automobile bodies. In these applications, the space frame allows thedesigner to create a very stiff, strong and stable structure that islight weight with a very high strength to weight ratio. An example innature of a similar matrix of regular polygons, fabricated from lightweight material that yields a highly stable and strong 3-dimensionalstructure is the beehive.

Overview of Manufacturing Processes

a. Overview and Requirements

Common ion exchange resins are made up of a polystyrene or cellulosebased backbone which is subsequently functionalized (aminated) into theanionic form usually via chloromethalation.

The manufacturing processes available to assemble the proposed matrixstructure can take advantage of the formability offered by thepolystyrene thermoplastic. Broadly, there are two paths open to thefabrication process. The first involves the formation of an assembledmatrix or mesh prior to its activation or functionalization. This allowsthe fabricator the flexibility of apply a broad selection of matureplastics fabrication processes to manufacture the air capture matrixthat would otherwise damage or destroy a functionally treated material.The primary concern is that the temperatures involved in meltingpolystyrene exceed the upper limit tolerance of the functionalizedmaterial.

The other fabrication path involves the use of pre-treated orfunctionalized material. This provides the option of working withpre-existing solid phase anion exchange materials albeit with somelimitations to the processing conditions in order to preserve the ioniccapabilities of the material. The limitation arises from the relativelylow temperature tolerance of the functional amine groups on thematerial. The upper temperature limit is in the range of 100 to 140° C.,well below the processing temperature necessary to fuse thethermoplastic material. Polystyrene has a T_(g) or glass transitiontemperature of approximately 100° C. and a melting point around 240° C.As a result, the material can be worked or formed near the upper safelimit for the functionalized material without melting the material whichwould destroy the functionality.

Experimentation with thermoplastic solid phase anion exchange materialshas shown that highly localized fusion bonding processes, such as spotwelding, may be for the assembly of the matrices as the heat-affectedzone is highly localized limiting the amount of functionality that isremoved by this processes. This process does not significantly impactthe bulk performance of the solid phase anion exchange materials.

b. Forming of Features and Assembly of Matrix

Selection of the shape of the features will be influenced, in part, bythe manufacturing processes available. For example, the choice of asimple polygon, such as a triangle, lends itself to some simple formingprocesses. Starting with a continuous sheet of either pre- orpost-functionalized polystyrene in roll form, a continuous formingoperation of creating a corrugation can be achieved by passing the sheetbetween two heated and matched contoured rollers. The precisely spacedrollers will capture the polystyrene, heat the material to its glasstransition temperature and impart the triangular shape. As thecorrugated sheet exits the rollers, they are allowed to cool to ensurethe shape takes a permanent set. For shapes that feature sharp bends orthat require more severe processing, the post-functionalized materialmay be more suitable to allow for higher temperature processing.

Another forming processes that yields similar results as in the aboveexample but produces formed sheets on a discrete basis, would be topress planar sheets between two heated and contoured platens underpressure. As before, the shape's features may dictate the formingtemperatures and therefore the selection of pre- or post-functionalizedmaterial.

Another forming process takes advantage of the existing technologiesapplied to the manufacturing of plastic parts. Specifically, polystyrenecan be heated and extruded or injection molded to form complex shapes.Whether discrete parts or continuously cast shapes, the final productwould then be functionalized after formation.

Yet another forming process involves the creation of a polystyrene foammaterial. With the addition of blow agents, an open-cell foam materialwould be created, the material cut into shape, and the pieces could befunctionalized prior to assembly. The open cell nature of the foam wouldallow airflow through the material.

Yet another manufacturing process involves the fusion of two or morediscrete pre-formed polystyrene parts. Through the application of highlylocalized high temperatures at or above the melting point of thematerial, it is possible to create a region where two or more pieces ofpolystyrene material would fuse together, e.g., by spot welding atdiscrete locations, or by seam welding along a continuous line. Thewelding method selected would be chosen to suite the final assembly, thetooling and the required robustness of the final part.

Finally, a matrix or unordered mesh of “noodle-like” strands of anionexchange material may be employed.

Design and Configuration Options for Air Capture Device

a. Overview and Requirements

The myriad of design options open for the matrix in terms of shapes andmanufacturing processes lends itself to numerous configurations of theair capture device. These configurations provide opportunity formodularization, customization to fit existing spaces and optimizationfor cost, efficiency and productization.

b. Cubic Forms

The cubic form lends itself to efficient packing arrangements andmodularization to support performance scale-up. An option is thedevelopment of a CO₂ capture system that is configured to fit intostandard 20 and 40 foot shipping containers wherein the air capturedevice will be substantially in a cubic form.

The air capture device also could be comprised of numerous, discretecubical modular sections that collectively provide the desired CO₂capture performance. This provides an opportunity to individuallyregenerate each section, one at a time, allowing for continuous,uninterrupted CO₂ capture.

c. Circular Forms

The circular form lends itself to a design that mimics a conventionalupdraft cooling tower. The disc could be configured to be a “solid” formwith uniform dimensions and features throughout its thickness. Airflowwould follow a path parallel to the axis of rotation of the disc.

In one arrangement, the air capture disc may be oriented horizontallywith a fan positioned above it to provide an updraft flow of air.

Another arrangement has the disc oriented vertically with the fan eitherin front or behind it. The disc may be arranged to slowly spin through atrough containing the chemicals to regenerate the active material.

In the retrofit market, the disc may be configured to fit within anexisting updraft cooling tower thereby taking advantage of the availabledraft.

Another configuration of the circular form is one wherein the device hasan annular cross section. In this configuration the processed air wouldmove radially through the sides of the structure, either inwards oroutwards depending on the installation.

d. Other Forms

There are many forms open to the design of the air capture deviceincluding those that are hollow. The configuration will be very muchdependant on the constraints of the installation, notwithstanding thosethat govern performance as previously indicated.

e. Non-Uniform Cross-Section Forms

Adjustments to the cross section may be necessary in some instances toensure uniform and efficient performance of the air capture device. Thismay lead to matrix configurations that have non-uniform cross sectionsand/or asymmetric profiles. Installation factors, enclosure designs andfan performance also may have a bearing on the final design and form ofthe matrix.

f. Matrix or Unordered Mesh Forms

A matrix or unordered mesh of “noodle-like” strands 1 mm thick by 1 mmwide are formed by slitting sheets of 1 mm thick commercially availableanion exchange material. The resulting “noodles” may then be looselypacked in a conduit, i.e., as shown in FIG. 2h , through which the airis directed.

Yet other structures that combine high surface area with low pressuredrop advantageously may be employed in accordance with the presentinvention.

In yet another aspect of the invention, the CO₂ captured from the air ispermanently sequestered. There are several discrete processes that canbe integrated to achieve permanent CO₂ sequestration. Referring to theattached drawing FIG. 7, two such processes are the air capture processsuch as described in our co-pending U.S. application Ser. No.11/209,962, filed Aug. 22, 2005, and a conventional industrialchlor-alkali process.

The chlor-alkali process is a common industrial process for themanufacture of commodity chlorine (Cl₂) and sodium hydroxide (NaOH) fromNaCl by electrolysis, e.g., of sea water, in an electrolytic cell. Theelectrochemical current causes chloride ions to migrate to the anodewhere it is collected as chlorine gas. Sodium hydroxide and hydrogenalso are formed. The overall process operates under the followingstoichiometric relationship:2H₂O+2NaCl→2NaOH+H₂+Cl₂ ΔH=+543 kJ/g-mole H₂  I.

Typical uses for chlorine include a bleaching agent for the pulp andpaper industry as well as a disinfectant agent. Sodium hydroxide is verycommon feed stack for numerous chemical and material manufacturingprocesses. The stream of hydrogen typically is considered a wastestream. Although some plants recover a portion of this waste stream foruse as a heat and power fuel source, the majority produced worldwide issimply flared, i.e., burned in the atmosphere for disposal. Theinvention in one aspect leverages the product and waste streams fromexisting chlor-alkali processes as well as the CO₂ product stream froman air capture system by inserting a Sabatier reduction process, whichis an exothermic process, downstream of the two previously mentionedprocesses. More particularly, in accordance with the present invention,the CO₂ collected in an air capture system, and the H₂ waste stream arecombined over a nickel or ruthenium catalyst at an elevated temperatureto reform these feed streams into C₄ (methane) and H₂O (water) under thestoichiometric conditions:CO₂+4H₂→CH₄+2H₂O ΔH=−165 kJ/mole @25° C.  II.

Thus, in accordance with one aspect of the present invention, carbondioxide from an air capture system and hydrogen gas from a Chlor-alkaliprocess are used as the feed streams for a Sabatier process. At lowpressure (approximately 1 bar) and 400° C. to 600° C. operatingtemperature, a product stream of methane and water vapour evolves. Toensure the permanent sequestration of the carbon in the methane, themethane gas may become the feedstock for the plastics processingindustry. The methane gas also may be burned as a synthetic fuel, orused as a feedstock for forming a liquid synthetic fuel.

Additional CO₂ sequestration can be achieved by further consolidation ofthe product streams of the chlor-alkali process. As above described, anH₂ stream is utilized to aid in the sequestration of CO₂ through theSabatier process. An NaOH stream also may be utilized to capture andsequester CO₂. Specifically, NaOH is a strong solvent for CO₂. Thus, byexposing the NaOH to the atmosphere, atmospheric CO₂ will react with theNaOH to form stable carbonates according to the following reactions:2NaOH+CO₂→Na₂CO₂+H₂O and,  III.NaOH+CO₂→NaHCO₃  IV.

These compounds occur naturally in the environment especially in theoceans. Thus, once the NaOH has completely reacted with the CO₂ in theatmosphere, the resulting carbonates can be introduced into the oceanwhere they are complementary to the marine life, and may be used by theindigenous marine life to form such vital structures as hard coral andshells. Another possibility is the direct injection of NaOH into theocean, changing the pH of the ocean which will allow the ocean to act asan atmospheric CO₂ collector as described in our aforesaid PCT PatentApplication Serial No. PCT/US06/029,238.

The chlorine product stream may be safely sequestered in the earth,e.g., via its reaction with natural magnesium hydroxide (MgOH). Thechlorine would be dissociated in water to produce hydrochloric acidwhich would react with the magnesium hydroxide producing magnesiumchloride, which has various industrial uses, and water. Anotherpossibility would be to leave the mineral salt in situ for permanentmineral sequestration.

Of course, the chlor-alkali product streams of NaOH, Cl₂ and HCl alsoare marketable commodities, and thus may be used for revenue generationas opposed to disposal.

Yet other possibilities include direct injection of CO₂ into deep wellsor deep ocean storage.

The present invention generates carbon credits at several stages. Onecarbon credit results from removal of CO₂ from the air. An additionalcarbon credit results from sequestration of the carbon as sodiumcarbonate. Two carbon credits are earned by conversion of the carboninto sodium bicarbonate. An additional carbon credit also can be earnedby acid injection of the carbon into minerals, i.e., to form salts, theCO₂ passed to deep well or deep ocean storage, or sequestration of thecarbon into plastics methane or synthetic fuel.

Various changes are possible without departing from the spirit and scopeof the invention. For example, NaOH has been described for reactivatingthe anionic exchange surface sorbent; however, the invention is notlimited to the use of sodium hydroxide as a sorbent, and other sorbentscapable of absorbing carbon dioxide, such as sodium carbonate may beused in the present invention. Also, while ion exchange material hasbeen described as a preferred material for forming the backbone of theair capture device, other air capture devices such as described in ouraforesaid PCT/US06/029238 and our PCT/US05/029979 advantageously may beemployed. Also, rather than cut the “noodles” from anion exchange sheetmaterial, threads of anion exchange material may be formed by crushinganionic exchange resin material, and extruding the crushed resinmaterial in a binder to form the “noodles” directly. Still otherapplications may be made without departing from the spirit and scope ofthe invention.

The invention claimed is:
 1. An apparatus for capture of CO₂ fromambient air, the apparatus comprising: a) an air capture devicecomprising a corrugated anion exchange material that captures CO₂ fromambient air upon exposure to the ambient air; b) a release mechanism forreleasing the captured CO₂ and regenerating the corrugated anionexchange material; and c) a concentrator that concentrates the acidicgas released from said corrugated anion exchange material.
 2. Theapparatus of claim 1, wherein the release mechanism comprises wetting ofthe corrugated anion exchange material by a liquid bath immersion orspray.
 3. The apparatus of claim 1, wherein the corrugated anionexchange material is formed as a circular disc comprising a spiral woundpattern of the corrugated anion exchange material.
 4. The apparatus ofclaim 3, wherein the circular disc is arranged vertically and slowlyspins through a trough containing a liquid used to regenerate thecorrugated anion exchange material.
 5. The apparatus of claim 1, whereinthe corrugated anion exchange material is formed as a plurality ofpolygons.
 6. The apparatus of claim 1, wherein the corrugated anionexchange material is formed as a plurality of squares, rectangles,triangles, trapezoids, pentagons, or hexagons.
 7. The apparatus of claim1, wherein the corrugated anion exchange material is shaped as aplurality of concentric layers.
 8. The apparatus of claim 1, wherein thecorrugated anion exchange material is shaped as a truncated cone.
 9. Theapparatus of claim 1, wherein the corrugated anion exchange material isformed as a mesh or honeycomb.
 10. The apparatus of claim 1, wherein thecorrugated anion exchange material is formed of an amine-functionalizedpolystyrene or cellulose-based anion exchange resin.
 11. The apparatusof claim 1, wherein the corrugated anion exchange material comprises asolid phase anion exchange material coated on an inert substratematerial.
 12. The apparatus of claim 1, wherein the apparatus isinstalled in a cooling tower.
 13. The apparatus of claim 1, wherein theapparatus further comprises either (i) a converter that convertsconcentrated CO₂ to a useful product, or (ii) an injector that injectsthe concentrated CO₂ into a deep well or into deep ocean storage. 14.The apparatus of claim 1, wherein liquid used to regenerate thecorrugated anion exchange material is a sodium hydroxide or sodiumcarbonate solution.
 15. The apparatus of claim 1, wherein the corrugatedanion exchange material comprises an amine.
 16. An apparatus for captureof CO₂ from ambient air, the apparatus comprising: a) an air capturedevice comprising an anion exchange material capable of absorbing CO₂from ambient air upon exposure to the ambient air; and b) a releasemechanism for releasing the captured CO₂ and regenerating the anionexchange material, wherein the geometric configuration of the anionexchange material comprises a 3-dimensional structure of repeatingshapes.
 17. The apparatus of claim 16 wherein said release mechanismcomprises a liquid bath immersion or spray.
 18. The apparatus of claim16 wherein the anion exchange material comprises functional aminegroups.
 19. The apparatus of claim 16 wherein the anion exchangematerial is a solid phase anion exchange material or is coated on asubstrate.
 20. The apparatus of claim 19, wherein the anion exchangematerial comprises a solid phase anion exchange material comprising afunctionalized polystyrene.
 21. The apparatus of claim 19, wherein theanion exchange material comprises a sheet of inert substrate materialcoated with the anion exchange material.
 22. The apparatus of claim 16,wherein the repeating shapes comprise regular and/or irregular polygonsthat may be of varying sizes and shapes.
 23. The apparatus of claim 22,wherein the repeating shapes comprise one or more of the shapes selectedfrom the group consisting of isosceles triangles, equilateral triangles,trapezoids, squares, and rectangles.
 24. The apparatus of claim 22,wherein the repeating shapes are of the same size and shape.
 25. Theapparatus of claim 16, wherein the shape, size and distribution of therepeating shapes vary over a length of the anion exchange material inorder to optimize the airflow of the ambient air.
 26. The apparatus ofclaim 16, wherein the anion exchange material is formed from sheets ofanion exchange material.
 27. The apparatus of claim 16, wherein theanion exchange material is a continuous corrugated layer.
 28. Theapparatus of claim 27, further comprising a planar layer that isco-joined with the continuous corrugated layer.
 29. The apparatus ofclaim 16, wherein the anion exchange material is formed as a circulardisc comprising a spiral wound pattern of the anion exchange material.30. The apparatus of claim 16, wherein the air capture device comprisesa plurality of concentric layers of anion exchange materialsubassemblies that fit snugly together.